Research On Detection Methods Of Perfluorinated Compounds And Organochlorine Pesticides In Environmental Matrices

Perfluorinated compounds(PFCs)and organochlorine pesticides(OCPs),as persistent organic pollutants,are bioaccumulative,can damage the nervous system,endanger human health,and exist stably in the environmental matrix.In recent years,countries around the world have established regulations to restrict the use of PFCs and OCPs.This paper took atmospheric particulate matter as the research system and 16kinds of PFCs as the research object,researched and established a new type of accelerated solvent extraction method to achieve sample extraction and purification in one step,using liquid chromatography tandem mass spectrometry to achieve reliable detection of PFCs;For the research system,25 kinds of OCPs were used as the research object,research and establishment of accelerated solvent extraction(ASE)and solid phase extraction(SPE)pretreatment analysis methods,using gas chromatography tandem mass spectrometry to achieve reliable detection of OCPs.In this paper,a liquid chromatography-mass spectrometry method for the analysis of 16 PFCs in atmospheric particulates has been established.The effects of spray voltage,capillary temperature,evaporation temperature,S-lens value,and number of micro-scans on the sensitivity of mass spectrometry were explored.Optimized mass spectrometry conditions:negative ion mode;spray voltage:3000 V;sheath gas:15 psi;auxiliary gas:10 psi;capillary temperature:250°C;evaporation temperature:300°C.Compare 5 different chromatographic columns,mobile phase type,mobile phase salt concentration and p H value,sample solvent,and obtain the best separation effect and chromatographic peak of 16 kinds of PFCs.Optimized liquid phase conditions:Fluoro Sep-RP Octyl(3u 60?150*2.1mm)column;mobile phase A was 400m M ammonium acetate/water/acetic acid(1/99/0.09,V/V/V),mobile phase B was Methanol.Gradient elution:0?2min,45%B;2?12min,45%?90%B;12?15min,90%B;15?18min,90%?100%B;18?28min,100%B.The flow rate was0.2 m L/min;the injection volume was 10?L.The column temperature was 25°C.The LOD was 0.006?0.5 ng·g^-1,the RSD is 0.66%?3.24%,the sensitivity was high,the repeatability is good,and it met the basic requirements of trace analysis of PFCs.In this paper,selective pressurized liquid extraction(SPLE)method was used to extract perfluorinated compounds in atmospheric particulates,and the factors affecting the extraction efficiency were systematically explored,including the type of adsorbent,the amount of adsorbent,the extraction temperature,and the number of cycles.The results showed that methanol was used as the extraction solvent,the extraction temperature was 120?,the static time was 10 min,the number of cycles was 3,the purge time was 180 s,and the washing ratio was 60%,which could achieve effective extraction.0.25g of graphitized carbon black had a better purification effect.Under the above conditions,the recovery of 16 PFCs at three levels(100ng/g,50ng/g,10ng/g)were 82.9%?118.5%,and the precision(RSD)was less than 8%.In the concentration range of 0.1?100 ng/g,the linear correlation coefficient was greater than 0.995,and the method had a good linear relationship.The detection limit and quantification limit of the method were 0.021?0.649 ng·g^-1and 0.070?2.165 ng·g^-1.The established method was used to determine and analyze the perfluorinated compounds in the total suspended particulates collected in the winter and summer from 2015?2019.The results showed that the method had high sensitivity,good reproducibility,reliability and simplicity,and it could meet the requirements for the detection of PFCs in real atmospheric particulate matter samples.In addition,this thesis also analyzed 25 kinds of organochlorine pesticides in the atmosphere.After the air sample was extracted by ASE,it was purified by LC-Florisil column and ENVI-Carb column,and determined by GC-MS.The recoveries of 25kinds of OCPs at three levels(15 ng,0.4 ng,0.1 ng)were 110%?130%,and RSD<30%.The detection limit of the method was 0.49?24.7 pg/m³,and the lower limit of determination was 1.97?98.81 pg/m³.The established method was used to determine the actual atmospheric samples.The results showed that the method was highly sensitive,reliable,and accurate,and was suitable for trace analysis of OCPs in real environmental air samples.